The present invention relates to novel calcilytic compounds, pharmaceutical compositions containing these compounds and their use as calcium receptor antagonists.
In mammals, extracellular Ca2+ is under rigid homeostatic control and regulates various processes such as blood clotting, nerve and muscle excitability, and proper bone formation. Extracellular Ca2+ inhibits the secretion of parathyroid hormone (xe2x80x9cPTHxe2x80x9d) from parathyroid cells, inhibits bone resorption by osteoclasts, and stimulates secretion of calcitonin from C-cells. Calcium receptor proteins enable certain specialized cells to respond to changes in extracellular Ca2+ concentration.
PTH is the principal endocrine factor regulating Ca2+ homeostasis in the blood and extracellular fluids. PTH, by acting on bone and kidney cells, increases the level of Ca2+ in the blood. This increase in extracellular Ca2+ then acts as a negative feedback signal, depressing PTH secretion. The reciprocal relationship between extracellular Ca2+ and PTH secretion forms an important mechanism maintaining bodily Ca2+ homeostasis.
Extracellular Ca2+ acts directly on parathyroid cells to regulate PTH secretion. The existence of a parathyroid cell surface protein which detects changes in extracellular Ca2+ has been confirmed. See Brown et al., Nature 366:574, 1993. In parathyroid cells, this protein, the calcium receptor, acts as a receptor for extracellular Ca2+, detects changes in the ion concentration of extracellular Ca2+, and initiates a functional cellular response, PTH secretion.
Extracellular Ca2+ influences various cell functions, reviewed in Nemeth et al., Cell Calcium 11:319, 1990. For example, extracellular Ca2+ plays a role in parafollicular (C-cells) and parathyroid cells. See Nemeth, Cell Calcium 11:323, 1990. The role of extracellular Ca2+ on bone osteoclasts has also been studied. See Zaidi, Bioscience Reports 10:493, 1990.
Various compounds are known to mimic the effects of extra-cellular Ca2+ on a calcium receptor molecule. Calcilytics are compounds able to inhibit calcium receptor activity, thereby causing a decrease in one or more calcium receptor activities evoked by extracellular Ca2+. Calcilytics are useful as lead molecules in the discovery, development, design, modification and/or construction of useful calcium modulators which are active at Ca2+ receptors. Such calcilytics are useful in the treatment of various disease states characterized by abnormal levels of one or more components, e.g., polypeptides such as hormones, enzymes or growth factors, the expression and/or secretion of which is regulated or affected by activity at one or more Ca2+ receptors. Target diseases or disorders for calcilytic compounds include diseases involving abnormal bone and mineral homeostasis.
Abnormal calcium homeostasis is characterized by one or more of the following activities: an abnormal increase or decrease in serum calcium; an abnormal increase or decrease in urinary excretion of calcium; an abnormal increase or decrease in bone calcium levels (for example, as assessed by bone mineral density measurements); an abnormal absorption of dietary calcium; an abnormal increase or decrease in the production and/or release of messengers which affect serum calcium levels such as PTH and calcitonin; and an abnormal change in the response elicited by messengers which affect serum calcium levels.
Thus, calcium receptor antagonists offer a unique approach towards the pharmacotherapy of diseases associated with abnormal bone or mineral homeostasis, such as hypoparathyroidism, osteosarcoma, periodontal disease, fracture healing, osteoarthritis, rheumatoid arthritis, Paget""s disease, humoral hypercalcemia associated with malignancy and fracture healing, and osteoporosis.
The present invention comprises novel calcium receptor antagonists represented by Formula (I) hereinbelow and their use as calcium receptor antagonists which are useful in the treatment of a variety of diseases associated with abnormal bone or mineral homeostasis, including but not limited to hypoparathyroidism, osteosarcoma, periodontal disease, fracture healing, osteoarthritis, rheumatoid arthritis, Paget""s disease, humoral hypercalcemia associated with malignancy and fracture healing, and osteoporosis.
The present invention further provides a method for antagonizing calcium receptors in an animal, including humans, which comprises administering to an animal in need thereof an effective amount of a compound of Formula (I), indicated hereinbelow.
The present invention further provides a method for increasing serum parathyroid levels in an animal, including humans, which comprises administering to an animal in need thereof an effective amount of a compound of Formula (I), indicated hereinbelow.
The compounds of the present invention are selected from Formula (I) hereinbelow: 
Formula (I)
and pharmaceutically acceptable salts and complexes thereof wherein:
n is an integer from 2 to 4;
X is selected from the group consisting of CN, NO2, Cl, F, and H;
Y is selected from the group consisting of Cl, F, Br, I and H;
Q and Z are, independently, selected from the group consisting of H, R1, SO2R1xe2x80x2, R1C(O)OR1xe2x80x3, SO2NR1xe2x80x2R1xe2x80x3, C(O)NR1xe2x80x2R1xe2x80x3, NR1xe2x80x2SO2Rxe2x80x31, wherein R1, R1xe2x80x2 and R1xe2x80x3 are independently selected from the group consisting of hydrogen, C1-4 alkyl, C3-6 cycloalkyl, C2-5 alkenyl, C2-5 alkynyl, heterocycloalkyl, aryl and aryl C1-4 alkyl; or R1xe2x80x2 and R1xe2x80x3 together form a 3 to 7 membered optionally substituted heterocyclic ring; wherein any substituents are selected from the group consisting of CN, aryl, CO2R, CO2NHR, OH, OR, NH2, halo, CF3, OCF3 and NO2; wherein R represents H, C1-4 alkyl, or C3-6 cycloalkyl;
W is CH2, O or NR1; and
D is O or H, provided that at least one D is H.
As used herein, xe2x80x9cAxe2x80x9d is phenyl or naphthyl, unsubstituted or substituted with any substituents being selected from the group consisting of OH, halo, CO2R1, C1-4 alkyl,C1-4 alkoxy, C3-6 cycloalkyl, OSO2R1, CN, NO2, OCF3, CF3, and CH2CF3, (CH2)nCO2H, (CH2)nCO2R1, and Oxe2x80x94(CH2)nCO2R1, wherein n is an integer from 0 to 3 0-3 and R1 represents C1-4 alkyl, C3-6 cycloalkyl, C3-6 cycloalkyl, heteroaryl or fused heteroaryl (wherein the hetero-ring can contain N, O or S and can be aromatic, dihydro or tetrahydro) unsubstituted or substituted with any substituents being selected from the group consisting of OH, OCH3, CH(CH3)2, halo, CO2R1, C1-4 alkyl, C1-4 alkoxy, C3-6cycloalkyl, CN, NO2, OCF3, CF3, CH2CF3, (CH2)nCO2R1, and Oxe2x80x94(CH2)nCO2R1.
As used herein, xe2x80x9calkylxe2x80x9d refers to an optionally substituted hydrocarbon group joined by single carbon-carbon bonds and having 1-20 carbon atoms joined together. The alkyl hydrocarbon group may be linear, branched or cyclic, saturated or unsaturated. The substituents are selected from F, Cl, Br, I, N, S and O. Preferably, no more than three substituents are present. More preferably, the alkyl has 1-12 carbon atoms and is unsubstituted. Preferably, the alkyl group is linear. Preferably, the alkyl group is saturated.
As used herein xe2x80x9clower alkylxe2x80x9d refers to C1-5 
As used herein xe2x80x9ccycloalkylxe2x80x9d refers to 3-7 membered carbocyclic rings
As used herein xe2x80x9cheterocycloalkylxe2x80x9d refers to 4, 5, 6 or 7 membered heterocyclic rings containing 1 to 2 heteroatoms selected from N,O, and S.
As used herein, xe2x80x9carylxe2x80x9d refers to an optionally substituted aromatic group with at least one ring having a conjugated pi- electron system, containing up to two conjugated or fused ring systems. Aryl includes carbocyclic aryl, heterocyclic aryl and biaryl groups, all of which may be optionally substituted.
The compounds of the present invention may contain one or more asymmetric carbon atoms and may exist in racemic and optically active forms. All of these compounds and diastereomers are contemplated to be within the scope of the present invention.
Preferred compounds of the present invention are selected from the group consisting of:
(R,S)-N-(4-Phenylbut-1-yl)-2-(2-chloro-1-cyanophenoxymethyl)morpholine; and
(R,S)-N-(4-phenylbut-1-yl)-2-(2,3-dichlorophenylcarbamoyl)morpholine.
Pharmaceutically acceptable salts are non-toxic salts in the amounts and concentrations at which they are administered.
Pharmaceutically acceptable salts include acid addition salts such as those containing sulfate, hydrochloride, fumarate, maleate, phosphate, sulfamate, acetate, citrate, lactate, tartrate, methanesulfonate, ethanesulfonate, benzenesulfonate, p-toluenesulfonate, cyclohexylsulfamate and quinate. A preferred salt is a hydrochloride. Pharmaceutically acceptable salts can be obtained from acids such as hydrochloric acid, maleic acid, sulfuric acid, phosphoric acid, sulfamic acid, acetic acid, citric acid, lactic acid, tartaric acid, malonic acid, methanesulfonic acid, ethanesulfonic acid, benzenesulfonic acid, p-toluenesulfonic acid, cyclohexylsulfamic acid, fumaric acid, and quinic acid.
Pharmaceutically acceptable salts also include basic addition salts such as those containing benzathine, chloroprocaine, choline, diethanolamine, ethylenediamine, meglumine, procaine, aluminum, calcium, lithium, magnesium, potassium, sodium, ammonium, alkylamine, and zinc, when acidic functional groups, such as carboxylic acid or phenol are present.
The present invention provides compounds of Formula (I) above which can be prepared using standard techniques. An overall strategy for preparing preferred compounds described herein can be carried out as described in this section. The examples which follow illustrate the synthesis of specific compounds. Using the protocols described herein as a model, one of ordinary skill in the art can readily produce other compounds of the present invention.
General Preparation
A general procedure used to synthesize many of the present compounds is described in Schemes 1 and 2. A solution of Boc-2-carboxymorpholine can be reduced with diborane solution in THF, the resulting alcohol, after treatment with 1 equivalent of NaH, can be reacted with an appropriately substituted arylfluoride such as 2-chloro-6-fluorobenzonitrile, to obtain the corresponding aryl ether. Removal of the Boc protecting group can be carried out under standard conditions (TFA/dichloromethane, or HCl/dioxane)(Scheme 1). After, neutralization, alkylation of the morpholino nitrogen can then be carried out by treatment with the appropriate alkyl halide or by reaction with the corresponding aldehyde under standard reductive amination conditions. 
In addition, some of the described compounds can be synthesized as described in Scheme 2. Formation of the acid fluoride of Boc-2-carboxymorpholine under standard conditions (cyanuric fluoride, pyridine) was followed by coupling with the corresponding aniline, for example 2,3-dichloroaniline to yield the corresponding amide. The reaction sequence from this point can proceed as described for Scheme 1.
Nuclear magnetic resonance spectra were recorded at either 250 or 400 MHz using, respectively, a Bruker AM 250 or Bruker AC 400 spectrometer. CDCl3 is deuteriochloroform, DMSO-d6 is hexadeuteriodimethylsulfoxide, and CD3OD is tetradeuteriomethanol. Chemical shifts are reported in parts per million (d) downfield from the internal standard tetramethylsilane. Abbreviations for NMR data are as follows: s=singlet, d=doublet, t=triplet, q=quartet, m=multiplet, dd=doublet of doublets, dt=doublet of triplets, app=apparent, br=broad. J indicates the NMR coupling constant measured in Hertz. Continuous wave infrared (IR) spectra were recorded on a Perkin-Elmer 683 infrared spectrometer, and Fourier transform infrared (FTIR) spectra were recorded on a Nicolet Impact 400 D infrared spectrometer. IR and FTIR spectra were recorded in transmission mode, and band positions are reported in inverse wavenumbers (cmxe2x88x921). Mass spectra were taken on either VG 70 FE, PE Syx API III, or VG ZAB HF instruments, using fast atom bombardment (FAB) or electrospray (ES) ionization techniques. Elemental analyses were obtained using a Perkin-Elmer 240C elemental analyzer. Melting points were taken on a Thomas-Hoover melting point apparatus and are uncorrected. All temperatures are reported in degrees Celsius.
Analtech Silica Gel GF and E. Merck Silica Gel 60 F-254 thin layer plates were used for thin layer chromatography. Both flash and gravity chromatography were carried out on E. Merck Kieselgel 60 (230-400 mesh) silica gel. Analytical and preparative HPLC were carried out on Rainin or Beckman chromatographs. ODS refers to an octadecylsilyl derivatized silica gel chromatographic support. 5xcexc Apex-ODS indicates an octadecylsilyl derivatized silica gel chromatographic support having a nominal particle size of 5xcexc, made by Jones Chromatography, Littleton, Colo. YMC ODS-AQ(copyright) is an ODS chromatographic support and is a registered trademark of YMC Co. Ltd., Kyoto, Japan. PRP-1(copyright) is a polymeric (styrene-divinylbenzene) chromatographic support, and is a registered trademark of Hamilton Co., Reno, Nev.) Celite(copyright) is a filter aid composed of acid-washed diatomaceous silica, and is a registered trademark of Manville Corp., Denver, Colo.